If, as looks increasingly possible, England's cricketers return from Australia triumphant this winter, lots of theories will doubtless be put forward to explain where it all went right.

Some will point to the dramatic return to form of Alastair Cook and Kevin Pietersen, England's batting heroes of the first two Tests. Others will cite the fact that Australia seem to have morphed, in very little time, from ruthless world beaters to ramshackle no-hopers, reminiscent in their ineptitude and disorganisation of the England team thrashed down under last time round in 2006/7. Others still will point to how Andy Flower, England's Zimbabwean coach, has instilled in a group of once distracted and faction-riven players an iron sense of discipline and self-belief.

One factor, however, is sure to be near the top of any such list – the remarkable contribution, both on and off the field, of England's off-spinner Graeme Swann.

In the past couple of years, 31-year-old Swann – "Swanny", as he is known in the dressing room and beyond – has emerged as England's most inspirational player. What's slightly surprising about this is that he is a spin bowler, and spin bowlers, in England at any rate, tend to be appendages rather than the bedrock of a team. Swan is not without his own maverick tendencies – he has a reputation as a joker and merciless mickey-taker – but he is also a consummate professional and a scarily effective bowler.

In an England line-up not short of wicket-taking stars (James Anderson is currently probably the world's best swing bowler), it is Swann above all who strikes fear into opposition batsmen. A purveyor of skiddy, sharply spun off-breaks, he has the invaluable knack of taking wickets when it matters, and is particularly lethal during the latter stages of a Test match on a deteriorating pitch.

But Swanny's appeal, and his importance to his teammates, extends well beyond his on-field exploits. In the past few years he has emerged as one of cricket's most attractive and colourful personalities, known as much for his Twitter updates (more than 111,000 followers) as for his skill with the ball.

He has a tendency to get into surreal scrapes: earlier this year, he was tested positive for drunken driving; his excuse was that he was driving to buy a screwdriver to release one of his cats from under his floorboards. He is also the lead singer of a Nottingham-based band named Dr Comfort and the Lurid Revelations (which probably tells you as much as you need or want to know about their music).

Within the English camp, too, he has emerged as a social linchpin, the main manufacturer of that vital ingredient for any sporting outfit – camaraderie. Cricketers often talk about the loneliness and boredom of touring, and it helps enormously if a team contains a larger-than-life character who is able to play the part of jester.

Throughout his career, Swann has naturally gravitated towards this role, a tendency that has occasionally seen him branded as a disruptive influence. In the current England set-up, though, his fun-loving presence and verbal boisterousness appear to have only a morale-boosting effect. That this is true is plainly evident from the video diaries Swann has been recording while in Australia, which thousands avidly follow on the English Cricket Board's website (www.ecb.co.uk).

In them, Swann comes across as a likable and intelligent man who is forever coming up with novel ways to keep his team-mates amused. He is a natural mimic and constantly ribs people about their appearance, be it Graham Gooch's waistline ("It's a good job this is a wide-angle shot") or the fact that "Cooky" (Alastair Cook) runs like Woody from Toy Story.

In one particularly funny scene, he eavesdrops on a press conference being given by fellow bowler Steven Finn. As the journalists listen respectfully, Swann's face appears in the frame and announces solemnly: "He's the most boring player I've ever played with."

The entry ends with a shot of Swann retiring to the bathroom nursing an imaginary nosebleed. Perhaps less successful is the moment when Swann adopts a mock Pakistani accent while talking to the team's spin bowling coach Mushtaq Ahmed, which suggests a certain naivety in the area of ethnic sensitivity. (Although, to give Swanny the benefit of the doubt, "Mushy" himself doesn't seem to care.)

Like many of the best cricketers, Swann hails from a family that has the game in its veins. He was born in Northampton in 1979, the son of schoolteacher parents Ray and Mavis. Ray, now retired, was a dedicated club cricketer who occasionally played at county second team level. Graeme's older brother, Alec, an opening batsman, also went into professional cricket, playing for Northamptonshire and then Lancashire; he is now a cricket reporter on the Northants Evening Telegraph.

Speaking to the Observer, Alec, who is two years older than his brother, recalls a happy and stable childhood dominated not just by cricket but by rugby and football well. Schoolwork, he says, was never really a priority: "Though Graeme's not a genius, he's quite an intelligent lad, but he got by without really, shall we say, exerting himself. He knew he was going to pass his exams and he did. He stayed on till A-levels but once he'd made his mind up he was going to play cricket then university wasn't an option. His attitude was, 'I'll be all right.'"

Having started playing for a local Northants team, Horton House, Swann progressed through the county and national junior ranks. On leaving school, he was signed by Northamptonshire, joining Alec. Within a year he was on the fringes of the national team, going on an "A" tour of South Africa and Zimbabwe in 1998, and a full England tour, also of South Africa, the following winter. But, as Alec recalls, this first taste of the big time wasn't really a success.

"He didn't play much cricket, he was always one of the back-up players. They thought he wasn't really up to it so he went back to county cricket. I think people saw him then as a bit of an upstart. England were a very experienced team at the time, and he was just a young lad, perhaps saying the wrong thing at the wrong time, and whoever was in charge just didn't take to him." So began a long interval during which Swann was a jobbing county cricketer, successful enough but never really a star. He grew increasingly frustrated at Northamptonshire, where he clashed with the South African team coach Kepler Wessels. The breakthrough came with his switch to Nottinghamshire in 2005; Alec says this was the "best move he ever made".

Nottinghamshire were one of the top teams in the country. Swann was encouraged to be himself, and started taking bucketloads of wickets. When the form of Monty Panesar, then England's first-choice spinner, dipped in 2007, Swann earned a recall to the England team. He has never really looked back, establishing himself as the side's talismanic bowler, becoming the first English spinner to take 10 wickets in a Test match since Jim Laker, earning the ECB Cricketer of the Year award this year, and in the process catapulting himself up the world bowling rankings to his current position of number two, behind South Africa's Dale Steyn.

So where did it all start going right for Swanny? According to his brother, nothing fundamental has changed; it just took a while for him to find both a county and an England set-up that suited his personality: "Ability-wise he could have done it regardless of who he played for. But it's not always a question of just being good enough. Someone's got to see you in the right time and the right place."

Former Wisden editor Matthew Engel agrees that Swann's problem earlier in his career says more about the coaches he played under than his abilities. "When he was on the way up, some of the more boring coaches, like Duncan Fletcher [England coach 1999-2007] and Kepler Wessels, didn't get him at all and he only fought his way into the England team when his numbers became unarguable."

Engel adds: "He's a big reason why the England team has improved. Not just because he takes wickets but because he isn't afraid. He plays as though he's having fun, which is important for a spinner because he has to purvey a kind of magic." It's a magic the whole country will be counting on in the coming weeks.